1. Field of the Invention
The present invention relates generally to cables for use in charging one automobile battery with another automobile battery.
2. Discussion of Background
Battery jumper cables generally comprise a pair of electrical connectors with clamps at opposing ends for securing to the terminals of a battery, one charging battery and one "dead" battery, or battery to be charged. The batteries must be connected in parallel to charge one from to the other. The tops of the batteries are typically marked with a "+" for positive and with a "-" for negative and usually the negative terminal is connected to ground. Furthermore, the cables are often color coded to help the user hook them up in proper relationship and sequence. However, if the top of the battery is dirty or the ambient lighting dim, it may be difficult to distinguish the terminals and determine which cable goes to which terminal. Furthermore, individuals tend to forget the proper cable connection sequence. Finally, there is sometimes the possibility when hooking the cables up to a "live" battery that hydrogen or other flammable gas, given off from the chemical activity in the battery, can be ignited by a spark and cause an explosion or fire in the engine compartment of the car.
To reduce the difficulty of connecting battery terminals during jump starting and the possibility of connecting the cables to the terminals improperly, several devices have been designed. See for example, U.S. Pat. No. 4,871,957 issued Oct. 1989 to Taranto, et al., U.S. Pat. No. 4,769,586 issued Sep. 1988 to Kazmierowicz, and U.S. Pat. No. 4,527,111 issued to Branham Jul. 1985. Branham uses electro-mechanical relays for correcting polarity without requiring reversal of one pair of cables. Taranto, et al. uses specialized clamps on the battery cables and repeated sampling of the voltages on the battery terminals to determine polarity. Kazmierowicz uses two sensing circuits, a switching circuit, and digital logic to assign cables according to correct polarity.
However, none of these systems is sufficiently durable, simple in design or inexpensive to manufacture.